Trolley shoe



W. F. GRAHAM June 23, 1931.

TROLLEY SHOE Filed June 10, 1930 F'Ia4 Inventor Attorney Patented June 23, 1931 UNITED, STATES PATENT OFFICE WALTER F. GRAHAM, OF RICHLAND, OHIO, ASSIGNOR TO THE OHIO BRASS COMPANY, F

MANSFIELD, OHIO, A CORPORATION OF NEW JERSEY TROLLEY SHOE Application filed June 10, 1930. Serial 1%. 460,204.

My invention relates" to a trolley shoe'or current collector which slides along the trolprob ability ley wire.

The object of my invention is to provide a shoe of ferrous metal which will possess hardened areas as compared with other areas to increase the life of the shoe and remove of the shoes breaking or cracking as is the case where the entire shoe is hardened.

Shoes of the, character shown and described herein are ordinarily made from low carbon steel, case hardened all over. This case hardening process if the one usually employed, namely that ofpacking the steel .forging in a carbonaceous material such as charcoal pulverized carbon, etc. and holding the article fora pre-determined period of time at a .temperature in the neighborhood of 1650 F., thereby obtaining a penetration of the carbon into the steel which is commonly referred to as a carburization or cementation of the steel, itwill be found that the entire surface has been penetrated to approximately to A with increasedcarbon and such pieces are hardened by quenching in a suitable medium as oil or water from above the critical point. 7

When shoes are prepared as outlinedabove, we find that not'only is the wearing surface in the groove highly hardened, but the lips or thinner portions forming the groove are extremely brittle and-such shoes are not entirely suitablefor the purpose intended due to certain portions being hardened which could better be left unhardened.

Also, we find that if it is attempted to draw the hardness of those portions which it is undesirable to have hardened as by SIIbJBCting the shoe to a-temperature of from 500 to 6009 F.,, that such temperature would be sufficient to reduce the hardness not'only in the flanges, but also in the bottom of the groove or wearing portion. 7

After analyzing the difliculties met with in standard shoes as described above and considerableexperimental work I found I was ableto produce a shoe which had only those portions desired highlyhardened while other portions were relatively soft.

In producing a shoe of this character my process broadly is to coat those surfaces which I do not wish to be hardened with a material which will prevent the carbon passing through and entering the steel.

In the accompanying drawing I Fig. 1 is a side view of one form of trolley shoe.

Fig. 2 is an end View of Fig. 1.

Fig. 3 is an opposite end view of Fig. 1.

Fig. 4 is a transverse sectional view on the line 4% of Fig. 1 and shows the relative hardness of different portions of the shoe on the line 47-4 of Fig. 1.

I might term my shoe a selectively case hardened shoe and such shoe is produced by preventing the penetration of the carbon in the sections or areas of the device in which the. high carbon material would be either unnecessary or injurious after the hardening process.

While there may be various methods of producing selective hardening the process which-I prefer to use is that of first cleaning the forging to remove all scale; then to copper plate the forging over its entire surface with a heavy coat of copper from a cyanide copper solution; then I remove the copper by grinding or wire brushing from such portions which I desire the carbon to penetrate intoduring the carburizing operation; this same result may be secured by painting or japanning those portions which are to be penetrated by the carbon, before copper plating and then removing the paint or japan after plating, thus leaving the portions to be hardened, free of copper; to then place the prepared shoe in a carbonaceous compound which will not attack the copper plate as for example hydro-carbonate of boneblack, and at a temperature of approximately 1650 F. for a suflicient length of time to obtain a penetration of the copper of approximately in the mild steel; then machine such portions of the forging as necessary. The machining operation, however, may be carried out before the carburizing process; then the carburized and machined shoe is hardened by giving it a double quench, that is, by first heating the shoe to approximately 1550 to can best beillustrated in'the soft core structure which engages the trolley wire will 1600 E, and then quenching in either water or oil, preferably the latter and this gives the shoe a refined low carbon core. The high carbon portion is'then hardened and refined by heating to about 1&25 F. and quenching in Water. The shoe is then subjected to a low drawing heat at a temperature under 375 1*.

which will remove hardening strains, but willbe sufliciently low to prevent the change of the martensitic structure to the softentroosti tic structure. V f

The shoe produced as above described will be of mild steel, that is,with carbon not over 25% with a hard wearing surface orsurfaces which come in contact with the trolley wire and soft, ductile portions which are liable tobesubjected to shocks or blows,

'The locations of the high carbon material 7 p figuresreferred to. In Fig; 4;;the high carbon portions are representedby the numerals .1 and 2 and the by the numeral 3 and the flanges .as l, The longitudinal extent of the hardened portion which may be indicated in 1 by the dotted line 5 and that of the hardened portion 2 by the dotted line 6.

When the shoe is new the hardened portion of course aftera period of time become worn through and thesofter portion 3 will then contact with 'thetrolley wire. The shoe is so constructed that the entire central portion may be worn 7 through before it is necessary to remove the through the portions 1 and 3 it 'shoe and therefore in order to give the user the benefit of the selective hardening the longitudinal central portion of the shoebelow the hardened portion 1 is likewise hardened and therefore when the trolley wire has out again con,-

tacts with a hardened portion 2 thereby decreasing the rate of wear.

it'SllP made of, clay,

' Shoeshave been vmade of high carbon steel which are, when hardened, of uniformhard ness throughout but such shoes are not satisfactory as' they check in hardening or they break throughv shocks and blows when in serivice, butwith fats'ho'e constructed as described coating, a coating of other non-ferrous metal which'will prevent 'he passage of carbon and withstandithe carburizing temperature; may

be used;

If desired the'enti're inner" surface of the groove beformed of hardened material which would be merely that of continuing the hardenedportionl or if desired the shoe may "be made of mild steel with the: entire groove is not 3 may be made hard by my process and the dI claimP-v L'A' trolley shoe comprising a body of content than the other portions contact surface.

that is, a solution of 5 surface and surface hardened leaving a soft mild steel core, but I prefer a shoe having only the portion 1 hardened or the portions 1 and 2, leaving in both cases the upstandinglips 4 unhardened and of mild steel.

If the portion tliroughthe bottomof the too thick, the portions 1, 2 and lipslleft soft. V v i l V 1 If the" material used is a low carbon steel with an alloy content, that is, carbon up to 25% and nickel, chromium, vanadium, etc.- of 4% more or less, the characteristics of the shoewill be considerably changed by the alloy content of nickel, etc., that is tougher and harder in the parts 1, 2 and 3 and tougher in the lips at as compared withcarbon' steel described. v Modifications will bev apparent to those f skilled in the art, but I'wish jtovbe limited only by my claims.

ferrous'material having a grooved portion with an elongated surface to rece1veand engage a trolley w1re,

V 2; A trolley shoe comprising a body of ferrous material having a grooved portlonwith 'an elongatedsurface to receive and engage a trolley wire, a portion of the body forming said grooved surface having a higher'carbon of the shoe a portion of the body forming said grooved surface having ahigher carbon content than the other portions of the shoe.

and the s aid higher carbOn content portion being harder than the other portions 3. A trolley shoe comprisinga body of mild steel with an elongated groovedportion "having a surface to contact with atrolley wire and the portion of the body forming the said surface having a'higher carbon content tha-n'the portions of h body adjace t the 4. A. trolley shoe comprising a body of mild steel and having a grooved portion, a portion of the surface within the groove being engaged by a trolley wire and'an exterior surface spaced from the said grooved surface, a

portion of the body forming the said internal surface and the external surface having a higher carbon content than the intermediate portion'of the'shoek V 5. Atrolley shoe'c'oinprising abody of mild steel and having a grooved portion, a portion of the'surfacelwithin the groove being engaged by a trolley wire and an exterior surface spaced, from the said grooved surface, a portion of the bodyjforming the said internal the external surface having a higher carbon contentthan the intermediate portion of the shoe, the higher carbon content portions having a higher degree-of hardness than the intermediate portion.

6. A trolley shoeof a; single pieceof fer- '8. A trolley shoe of a single piece of alloysteel having a groove with a surface to engage a trolley conductor, a portion of the shoe having a higher carbon content than the other portion of the shoe forming the balance of the surface and hardened.

9. A trolley shoe having a U shaped grooved portion, the lips of the groove being of mild steel and the other portion of the groove being of higher carbon hardened steel.

10. A trolley shoe of hardened steel having a grooved portion with upstanding side walls of mild steel.

11. The method of forming a trolley shoe comprising forging a body of mild steel to proper shape having an elongated portion of U shaped cross-section, then coating certain portions with a material which will prevent the passage of carbon therethrough, then packing the shoe in a carbonaceous material then subjecting the shoe and material to a sustained temperature for a predetermined time to obtain a penetration of carbon from the carbonaceous material into the shoe and increase the carbon content at the uncoated portions.

12. The method of forming a trolley shoe comprising forging'a body of mild steel to proper shape having an elongated portion of U shaped cross-section, then coating certain portions with a material which will prevent the passage of carbon therethrough, then packing the shoe in a carbonaceous material, then subjecting the shoe and material to a sustained temperature for a predetermined time to obtain a penetration of carbon from the carbonaceous material into the shoe and increase the carbon content at the uncoated portions, then quenching the shoe from an elevated temperature toharden those portions having excess carbon.

13. The method of forming a trolley shoe comprising forging a body of mild steel toproper shape having an elongated portion of U shaped cross-section, then'coating certain portions with a plating of non-ferrous metal which will prevent the passage of carbon therethrough, then packing the shoe in a carbonaceous material, then subjecting the shoe and material to a sustained temperature for a predetermined time to obtain a penetration of carbon from the carbonaceous material into the shoe and increase the carbon content at the uncoated portion.

1A. The method of forming a trolley shoe comprising forging a body of mild steel to proper shape having an elongated portion of U shaped cross-section, then coating certain portions with a plating of copper which will prevent the passage of carbon therethrough, then packing the shoe in a carbonaceous material, then subjecting the shoe and material to a sustained temperature for a predetermined time to obtain a penetration of carbon 1ro1n the carbonaceous material into the shoe and increase the carbon content at the uncoated portion.

15. A trolley shoe of mild steel having its wearing portions of hardened steel.

16. A grooved trolley shoe comprising a body of mild steel of a carbon content up to 25% and having a portion subjected to wear through contact with a trolley wire, the said portion having a higher carbon content and of a greater hardness than the adjacent portion.

17. A trolley shoe of alloy steel having a 1:

carbon content up to 25% and an alloying material up to 4% and having its wearing portion harder than other portions.

In testimony whereof I afliX my signature.

WALTER F. GRAHAM. 

